The $1.5bn (£1.17bn) project is designed to give scientists a better understanding of solar wind and geomagnetic storms that risk wreaking chaos on Earth by knocking out the power grid.
The probe will get within 3.8 million miles (6 million kilometres) of the sun's surface after travelling at a record-breaking 430,000 mph.
From Earth it will travel 93 million miles before it gets within four percent of the Sun's surface.
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